The servicing and maintenance of machines and equipment in industry in which unexpected energization or start up of the machines or equipment, or release of stored energy could cause injury to employees, requires the use of warning data-tags so that employees will not accidentally re-energize the equipment. The use of such tags is not only mandated by common sense but in some cases government regulations require their use and sets standards for the tags to prevent inadvertent or accidental removal. Some OSHA regulations, such as law 29 CFR .sctn. 1910.147 published in the Federal Register Vol. 54, No. 169, 36687-36696 (Sep. 1, 1989), require a data-tag with a minimum unlocking strength of no less than 50 pounds.
A suitable data-tag should be constructed from materials which are resistant to severe environmental conditions, readily assembled and yet substantial enough to prevent its removal except with the use of excessive force or a tool. The data-tag should be imprintable with instructions that are clearly legible and will not become illegible over time under the conditions of use. A system which allows high volume, computer printing of a plurality of data-tags with variable information is also desirable.
The most common type of data-tag presently being used are vinyl or paper tags which are relatively inexpensive. However, vinyl and paper are not strong enough in some situations, especially in severe winds which can cause the tag to rip and blow away. Also vinyl and paper lose strength with aging in a relatively short period of time and have low heat resistance.
It is often desirable to add information to a data-tag either by printing or writing on the surface of the substrate. The user may also wish to add information to a large number of labels by typewriter or computer printer. Typewriters can be used for most types of labels and data-tags where individual labels are to be imprinted but they are slow and not suitable for high volume printing. To print information with a computer printer it is usual to feed a sheet of labels to an impact printer and separate the individual labels after removal of the printed sheet from the printer. In this way a large number can be printed at a time, however, the print quality of impact printers is not always satisfactory nor resistant to wear over the time of use. Non-impact printers such as laser printers are known for their speed and the quality, clarity and durability of the printing and are increasingly found in the work place. However, laser printers can reach temperatures of up to about 300.degree. F. and are not suitable for printing on vinyl.
Polyester has a much higher melting point than vinyl. While vinyl may melt or deform at temperatures as low as 150.degree. F., polyester is usable at temperatures of 225.degree.-300.degree. F. Therefore, not only can polyester be used in higher temperature environments where vinyl would melt or deform if exposed to heat, polyester based sheets can be fed through a laser printer.
In electrostatographic imaging processes such as laser printing or electrophotographic copying, a pattern or image formed by electrostatically charged thermoplastic particles of toner powder is transferred from the surface of a photoconductor or other dielectric surface to a receiver material which can be in the form of sheets or a continuous web roll. The transfer is normally accomplished by electrically charging the receiver surface to a polarity opposite to that of the toner particles and then contacting the receiver with the photoconductive surface. After transfer of the toner particles, the receiver is passed through heated rollers to fuse the toner to its surface. Commonly, the receiver for dry toner particles is plain paper and many thermoplastic toner materials adhere well to paper and form a satisfactory image or printing. When it is desired, however, to form a toner image on a plastic substrate, for example, a transparency or a label, problems arise. One problem is the difficulty of adhesion of the usual toner particles to the kinds of substrates usually preferred. A particularly preferred type of transparency substrate for toner printing is a polyester substrate such as a film of biaxially oriented poly(ethylene terephthalate). Although, this kind of substrate has desirable physical properties such as thermal stability and can withstand the high temperatures encountered in laser printers, the polyester surface does not adhere well to the usual thermoplastic toner powders.
To improve toner adhesion to plastic receivers, the prior art has applied various coatings to their surfaces. In some instances these coatings may have improved the adhesion of toner to the receiver, but other problems have occurred. For example, coated plastic sheets can be difficult to feed and transport rapidly and, when stacked in packages or in feeding trays and equilibrated to machine environment, the sheets often block or stick together. This results in multifeeds and jams.
The prior art discloses toner receiving substrates having surface coatings that provide certain properties. For example, Hart discloses in U.S. Pat. No. 5,130,189 an imagable copy film comprising a biaxially oriented polyester substrate with an acrylic and/or methacrylic receiving layer which improves the adhesion to the substrate of toner powder applied by an electrostatic copying process, such as with a copier or laser printer. The receiving layer can also contain finely divided filler particles, for example silica, as an anti-blocking agent. A wax coating on the receiving layer can also be incorporated as an anti-static to reduce the sticking together of the sheets.
In most applications it is necessary to coat the polyester substrate with a receptive surface to receive printing and/or writing thereon. The receptive surface should be resistant to the temperatures reached by a laser printer to allow computer printing of the surface with a laser printer and it should be compatible with coloring pigments so that distinctive colored labels can be produced. In many applications, it is necessary to label the tag at the time it is applied and the coating should have good pencil receptivity.
In general, because of the design of laser printers which use a curved paper path that restricts the paper to a relatively thin and flexible profile, the thickness of a polyester substrate must conform to a relatively narrow range. Material which is too thick will not feed well through a laser printer while material which is too thin could be slightly distorted and shrunk by the heat of the fuser roll causing the film to buckle or curl and later jam in the laser printer. Also unsuitable for use with laser printers are labels and tags having low melting adhesives or thin protective plastic films as components. Adhesives which melt could ooze onto the feed rollers or heat rollers and leave a gum like layer or splotches that could damage the printer and require expensive repairs.
Polyester substrates are strong and tear resistant. However, once a notch is provided at an edge of a polyester sheet it can be readily torn. A sheet of data-tags formed on a polyester substrate requires a means for separating the individual data-tags from the sheet. This is commonly a tear line of perforations or spaced slits which allows the user to rip the tag out of a sheet of tags. Older patterns in which the holes or slits are relatively large and wide apart can result in random tears in the substrate. Selection of suitable tear lines for a polyester sheet of tags is very important. In known printing operations which operate by tractor feeding continuous folded sheets of paper to the printer, the sheets are separated from each other and from the tractor feed line of holes by lines of micro perforations which minimize random tearing when the sheets are pulled apart.
Hosoya discloses in U.S. Pat. No. 4,688,826 a folded multiple sheet shipping form in which the sheet form is preprinted with shipping information on a non-impact printer or a laser printer before assembling into a label protected by an adhesively backed film. There is no suggestion of a polyester based form.
Burt in U.S. Pat. No. 4,951,970 discloses a protective label system for use with a computer printer having a plurality of removable labels adhesively attached to a carrier sheet which can be serially printed on said printer in a continuous manner and afterwards covered with a protective film which is part of the label form. The removable labels are preferably polyester.
Thoese in U.S. Pat. No. 4,202,923 discloses a drawing layer for a polyester film comprising a cellulose ester cross linked by a formaldehyde resin.
Although polyester is a strong base material for a data-tag, a tie or wire fastener easily cuts through it and a 5 mil thick data-tag rips out with less than 10 LB of pull. It is desirable therefore to reinforce the mounting hole. Known data-tags use reinforcing grommets or eyelets in their mounting holes. Such grommets or eyelets are made from brass, although some stainless steel grommets are used. The metal has to be ductile enough to bend easily in an eyeletting tool which is required to assemble the grommet to a tag. Metal grommets always require a tool and a two step operation to assemble. Metal grommets have the disadvantage that when made of less expensive materials they can rust and even more importantly, they are conductive which is a disadvantage for electrical use. When warning tags are used on high voltage transmission lines, intense electric fields are often present that may cause arcing or flashing when metal grommets are used. A non-conducting reinforcer which will increase the pull strength at the mounting hole is desirable for industrial use. Plastic snap-grommets are known for use with large banners and are designed to receive ropes for raising or holding the banners in place. Such grommets have thick broad shoulders for strength and are far too thick for mounting on the relatively small warning tags used on industrial equipment. Such plastic snap-grommets require use of a tool for assembly, are readily pried apart and are expensive. In industrial use it is frequently necessary to attach the data-tag to a lock shank. Such a large grommet is too bulky for use with a lock shank. It is so thick that you cannot thread the curved portion of the lock shank through it.
Accordingly, it is an object of this invention to provide a reinforced data-tag system which can be serially printed in a laser printer in a continuous manner by providing a thermally stable polyester substrate from 3 to 7 mils (0.075 to 0.175 mm) thick with a receptive surface coated thereon for receiving toner images, and having a mounting hole in which a non-conducting, locking, plastic, two-piece snap-grommet can be mounted.
It is another object of this invention to provide a matrix of a plurality of data-tags formed on the polyester substrate for feeding through a laser printer.
It is another object of this invention to provide a data-tag system in which a portion of each data-tag is reserved for receiving variable customized information.
It is another object of this invention to provide tear lines on the polyester substrate which allow separation of the individual data-tags without tearing of the data-tag.
It is another object of this invention to provide a non-conducting, locking, two-piece, plastic snap-grommet which can be hand assembled in the mounting hole of the data-tag.
It is another object of this invention to provide a snap-grommet which can accommodate a lock shank.
It is yet another object of this invention to provide a reinforced data-tag having a pull strength of no less than about 50 pounds (22.7 kg).
While the novel aspects of the invention are set forth with particularity in the appended claims, the invention itself, together with further objects and advantages thereof may be more readily understood by reference to the following detailed description of a presently preferred embodiment of the invention taken in conjunction with the following drawings in which: